I'm not sure if it exactly has to do with memory leakage ...

If i work on a scenery and keep adding stuff, erase stuff, change scene settings and look, change atmo, exchange objects, add eco, erase eco, change eco, activate displacement, deactivate displacement and, and, and  - the resources logically will get lower and lower earlier or later.

The special things, Vue allows me to do, plus handling billions of polygons - i'm not sure, if it's that easy, to keep everything perfect clean in the memory organization. It must be pretty complicated, to write the code for the program, to do all that and the same time write routines, which suppose to decide, what's still needed or not. What should be kept in storage or not. Which parts of the scene, erased or not, are still related to each other.
And all that with endless possible given situations or scenery setups ...

That you will have your memory filled with certain things after a while working and changing many different or a few heavy impact details, is logical. And if i notice, that resources get lower, well, the cleanest way really is to save the scene (then only the scene related data will be saved) and restart (taking just seconds), to get the most resources back and use only what's needed.

And - i'm not sure, if they ever will be able to work out a perfect resources routine, which can decide by itself, what to keep or not to keep in memory ...
(Just let C4D, 3DSMax or whatever the big 3D packages are called, create and handle procedural terrains and special texturing and immense plant use - and keep their memory handling clean. Since they don't use special stuff like ecosystem and whatever Vue is specialized in, than those application for sure have an easier job, to handle their resources ... and make them look good, in whatever they can do ...).